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It always runs downhill

By
Home Inspector with Home Inspector for ASPEC Residential Services, LLC

The ole' plumbing adage (by adding a few letters to the beginning of the title) is most certainly true and I'd like to touch on just how to help move it "down that hill".  Nothing like reading about sewage flow, no? Or you can just skip the reading, look at the pictures, leave a comment, and move on with your day :)

The per-foot drop rate for wastewater and drainage pipes ideally is 1/4". In other words, the ideal number ratio to keep things movin' along properly.  And if the drain doesn't have enough slope, obviously the waste isn't going to flow properly. On the other hand, if there is too much or excessive slope, as shown in the picture (the green pipe), solids and liquids could start separating (a thumbs down installation).

pitch pipe

This installation may lead to "mounding" or collecting of solid waste, that couldeventually lead to blockages and/or impeded drainage. Something you, obviously, never want to happen.  There is a point to mention on this though.  If that excessive slope is 45°-to-vertical, well, gravity definitely will be a factor, and things will almost certainly drain one way or the other (in other words, a thumbs up installation). 

Pitch graphic

So to sum it all up, drain pipes should slope 1/4" to 1/2" per foot and/or be vertical.  Or just have a good plumber install/repair your plumbing the right way and then you won't have to worry about having a plumber on speed dial to keep coming over to clean your pipes out.

 

Captain Wayne - Rowlett Real Estate School
Rowlett Real Estate School - Panama City, FL
Rowlett Real Estate School / Owner and Instructor

Great blog Joshua, your title is the same thing my ol pappy use to say.

Oct 03, 2013 11:13 AM
Sharon Parisi
United Real Estate Dallas - Dallas, TX
Dallas Homes

Joshua, your graphics should grab everyone's attention.  In Texas, where the soil moves and sometimes causes pipes to move as a result, it is a good idea to check the slope of pipes.

Oct 03, 2013 12:24 PM
Robert Butler
Aspect Inspection - Montreal West Island, QC
Montreal Home Inspector | Aspect Inspection

I liked your graphic. I clearly shows the problem. Those slope effects can't be seen through the pipes and this is where amateurs get into trouble.

Just about any handy person can cut and glue pipes together. True plumbing is much more than that.

Feb 08, 2014 04:59 AM